Reliable identification of “truly low” thromboembolic risk in patients initially diagnosed with “lone” atrial fibrillation: the Belgrade atrial fibrillation study - Potpara, T S; Polovina, M M; Licina, M M; Marinkovic, J M; Prostran, M S; Lip, G Y (Circ Arrhythm Electrophysiol, 2012)